/*
 * Lazy Load - jQuery plugin for lazy loading images
 *
 * Copyright (c) 2007-2013 Mika Tuupola
 *
 * Licensed under the MIT license:
 *   http://www.opensource.org/licenses/mit-license.php
 *
 * Project home:
 *   http://www.appelsiini.net/projects/lazyload
 *
 * Version:  1.9.1
 *
 */

(function($, window, document, undefined) {
      var $window = $(window);
  
      $.fn.lazyload = function(options) {
          var elements = this;
          var $container;
          var settings = {
              threshold       : 0,
              failure_limit   : 0,
              event           : "scroll",
              effect          : "show",
              container       : window,
              data_attribute  : "original",
              skip_invisible  : true,
              appear          : null,
              load            : null,
              placeholder     : ""
          };
  
          function update() {
              var counter = 0;
  
              elements.each(function() {
                  var $this = $(this);
                  if (settings.skip_invisible && !$this.is(":visible")) {
                      return;
                  }
                  if ($.abovethetop(this, settings) ||
                      $.leftofbegin(this, settings)) {
                          /* Nothing. */
                  } else if (!$.belowthefold(this, settings) &&
                      !$.rightoffold(this, settings)) {
                          $this.trigger("appear");
                          /* if we found an image we'll load, reset the counter */
                          counter = 0;
                  } else {
                      if (++counter > settings.failure_limit) {
                          return false;
                      }
                  }
              });
  
          }
  
          if(options) {
              /* Maintain BC for a couple of versions. */
              if (undefined !== options.failurelimit) {
                  options.failure_limit = options.failurelimit;
                  delete options.failurelimit;
              }
              if (undefined !== options.effectspeed) {
                  options.effect_speed = options.effectspeed;
                  delete options.effectspeed;
              }
  
              $.extend(settings, options);
          }
  
          /* Cache container as jQuery as object. */
          $container = (settings.container === undefined ||
                        settings.container === window) ? $window : $(settings.container);
  
          /* Fire one scroll event per scroll. Not one scroll event per image. */
          if (0 === settings.event.indexOf("scroll")) {
              $container.bind(settings.event, function() {
                  return update();
              });
          }
  
          this.each(function() {
              var self = this;
              var $self = $(self);
  
              self.loaded = false;
  
              /* If no src attribute given use data:uri. */
              if ($self.attr("src") === undefined || $self.attr("src") === false) {
                  if ($self.is("img")) {
                      $self.attr("src", settings.placeholder);
                  }
              }
  
              /* When appear is triggered load original image. */
              $self.one("appear", function() {
                  if (!this.loaded) {
                      if (settings.appear) {
                          var elements_left = elements.length;
                          settings.appear.call(self, elements_left, settings);
                      }
                      $("<img />")
                          .bind("load", function() {
  
                              var original = $self.attr("data-" + settings.data_attribute);
                              $self.hide();
                              if ($self.is("img")) {
                                  $self.attr("src", original);
                              } else {
                                  $self.css("background-image", "url('" + original + "')");
                              }
                              $self[settings.effect](settings.effect_speed);
  
                              self.loaded = true;
  
                              /* Remove image from array so it is not looped next time. */
                              var temp = $.grep(elements, function(element) {
                                  return !element.loaded;
                              });
                              elements = $(temp);
  
                              if (settings.load) {
                                  var elements_left = elements.length;
                                  settings.load.call(self, elements_left, settings);
                              }
                          })
                          .attr("src", $self.attr("data-" + settings.data_attribute));
                  }
              });
  
              /* When wanted event is triggered load original image */
              /* by triggering appear.                              */
              if (0 !== settings.event.indexOf("scroll")) {
                  $self.bind(settings.event, function() {
                      if (!self.loaded) {
                          $self.trigger("appear");
                      }
                  });
              }
          });
  
          /* Check if something appears when window is resized. */
          $window.bind("resize", function() {
              update();
          });
  
          /* With IOS5 force loading images when navigating with back button. */
          /* Non optimal workaround. */
          if ((/(?:iphone|ipod|ipad).*os 5/gi).test(navigator.appVersion)) {
              $window.bind("pageshow", function(event) {
                  if (event.originalEvent && event.originalEvent.persisted) {
                      elements.each(function() {
                          $(this).trigger("appear");
                      });
                  }
              });
          }
  
          /* Force initial check if images should appear. */
          $(document).ready(function() {
              update();
          });
  
          return this;
      };
  
      /* Convenience methods in jQuery namespace.           */
      /* Use as  $.belowthefold(element, {threshold : 100, container : window}) */
  
      $.belowthefold = function(element, settings) {
          var fold;
  
          if (settings.container === undefined || settings.container === window) {
              fold = (window.innerHeight ? window.innerHeight : $window.height()) + $window.scrollTop();
          } else {
              fold = $(settings.container).offset().top + $(settings.container).height();
          }
  
          return fold <= $(element).offset().top - settings.threshold;
      };
  
      $.rightoffold = function(element, settings) {
          var fold;
  
          if (settings.container === undefined || settings.container === window) {
              fold = $window.width() + $window.scrollLeft();
          } else {
              fold = $(settings.container).offset().left + $(settings.container).width();
          }
  
          return fold <= $(element).offset().left - settings.threshold;
      };
  
      $.abovethetop = function(element, settings) {
          var fold;
  
          if (settings.container === undefined || settings.container === window) {
              fold = $window.scrollTop();
          } else {
              fold = $(settings.container).offset().top;
          }
  
          return fold >= $(element).offset().top + settings.threshold  + $(element).height();
      };
  
      $.leftofbegin = function(element, settings) {
          var fold;
  
          if (settings.container === undefined || settings.container === window) {
              fold = $window.scrollLeft();
          } else {
              fold = $(settings.container).offset().left;
          }
  
          return fold >= $(element).offset().left + settings.threshold + $(element).width();
      };
  
      $.inviewport = function(element, settings) {
           return !$.rightoffold(element, settings) && !$.leftofbegin(element, settings) &&
                  !$.belowthefold(element, settings) && !$.abovethetop(element, settings);
       };
  
      /* Custom selectors for your convenience.   */
      /* Use as $("img:below-the-fold").something() or */
      /* $("img").filter(":below-the-fold").something() which is faster */
  
      $.extend($.expr[":"], {
          "below-the-fold" : function(a) { return $.belowthefold(a, {threshold : 0}); },
          "above-the-top"  : function(a) { return !$.belowthefold(a, {threshold : 0}); },
          "right-of-screen": function(a) { return $.rightoffold(a, {threshold : 0}); },
          "left-of-screen" : function(a) { return !$.rightoffold(a, {threshold : 0}); },
          "in-viewport"    : function(a) { return $.inviewport(a, {threshold : 0}); },
          /* Maintain BC for couple of versions. */
          "above-the-fold" : function(a) { return !$.belowthefold(a, {threshold : 0}); },
          "right-of-fold"  : function(a) { return $.rightoffold(a, {threshold : 0}); },
          "left-of-fold"   : function(a) { return !$.rightoffold(a, {threshold : 0}); }
      });
  
  })(jQuery, window, document);